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MEK vs Acetone

Brambo

Well Known Member
What is the difference between Acetone and MEK. I have read in several discussions about fiberglass work where some people use acetone and others use MEK as a cleaner/thinner.

Bill Rambo
RV-7A
 
The MEK is more agressive than Acetone. Both are not to be breathed in any amounts and wear solvent resistant gloves when using them.....and Flammable
 
WEST and Acetone...

What is the difference between Acetone and MEK. I have read in several discussions about fiberglass work where some people use acetone and others use MEK as a cleaner/thinner.

Bill Rambo
RV-7A

If you are using the WEST products....

The WEST Epoxy User's Manual seems to prefer acetone....

....lacquer thinner, acetone or other appropriate solvent....

...but I guess MEK might fall under the "other appropriate solvent" category...:)

http://www.westsystem.com/frames/tier1/usingepoxy.htm

gil A
 
FWIW: My understanding has been that MEK and Acetone are essentially the same except for the speed with which they evaporate. Both are nasty over a long period of time so I suggest wearing gloves and have good ventilation, e.g., don't use in closed rooms, at least not for big jobs.

Chris
 
Equally bad for you...

FWIW: My understanding has been that MEK and Acetone are essentially the same except for the speed with which they evaporate. Both are nasty over a long period of time so I suggest wearing gloves and have good ventilation, e.g., don't use in closed rooms, at least not for big jobs.

Chris

Chris... good point....

I went to the MSDS and they both look equally bad...:(

MEK

Emergency Overview
--------------------------
DANGER! EXTREMELY FLAMMABLE LIQUID AND VAPOR. VAPOR MAY CAUSE FLASH FIRE. HARMFUL OR FATAL IF SWALLOWED. HARMFUL IF INHALED OR ABSORBED THROUGH SKIN. AFFECTS CENTRAL NERVOUS SYSTEM. CAUSES IRRITATION TO SKIN, EYES AND RESPIRATORY TRACT.

---------------------------------
Health Rating: 2 - Moderate (Life)
Flammability Rating: 3 - Severe (Flammable)
Reactivity Rating: 1 - Slight
Contact Rating: 2 - Moderate
Lab Protective Equip: GOGGLES & SHIELD; LAB COAT & APRON; VENT HOOD; PROPER GLOVES; CLASS B EXTINGUISHER
Storage Color Code: Red (Flammable)
---------------------------------

Potential Health Effects
----------------------------------

Inhalation:
Causes irritation to the nose and throat. Concentrations above the TLV may cause headache, dizziness, nausea, shortness of breath, and vomiting. Higher concentrations may cause central nervous system depression and unconsciousness.
Ingestion:
May produce abdominal pain, nausea. Aspiration into lungs can produce severe lung damage and is a medical emergency. Other symptoms expected to parallel inhalation.
Skin Contact:
Causes irritation to skin. Symptoms include redness, itching, and pain. May be absorbed through the skin with possible systemic effects.
Eye Contact:
Vapors are irritating to the eyes. Splashes can produce painful irritation and eye damage.
Chronic Exposure:
Prolonged skin contact may defat the skin and produce dermatitis. Chronic exposure may cause central nervous system effects.
Aggravation of Pre-existing Conditions:
Persons with pre-existing skin disorders or eye problems or impaired respiratory function may be more susceptible to the effects of the substance.

ACETONE

Emergency Overview
--------------------------
DANGER! EXTREMELY FLAMMABLE LIQUID AND VAPOR. VAPOR MAY CAUSE FLASH FIRE. HARMFUL IF SWALLOWED OR INHALED. CAUSES IRRITATION TO SKIN, EYES AND RESPIRATORY TRACT. AFFECTS CENTRAL NERVOUS SYSTEM.

---------------------------------
Health Rating: 2 - Moderate
Flammability Rating: 3 - Severe (Flammable)
Reactivity Rating: 0 - None
Contact Rating: 3 - Severe
Lab Protective Equip: GOGGLES & SHIELD; LAB COAT & APRON; VENT HOOD; PROPER GLOVES; CLASS B EXTINGUISHER
Storage Color Code: Red (Flammable)
---------------------------------

Potential Health Effects
----------------------------------

Inhalation:
Inhalation of vapors irritates the respiratory tract. May cause coughing, dizziness, dullness, and headache. Higher concentrations can produce central nervous system depression, narcosis, and unconsciousness.
Ingestion:
Swallowing small amounts is not likely to produce harmful effects. Ingestion of larger amounts may produce abdominal pain, nausea and vomiting. Aspiration into lungs can produce severe lung damage and is a medical emergency. Other symptoms are expected to parallel inhalation.
Skin Contact:
Irritating due to defatting action on skin. Causes redness, pain, drying and cracking of the skin.
Eye Contact:
Vapors are irritating to the eyes. Splashes may cause severe irritation, with stinging, tearing, redness and pain.
Chronic Exposure:
Prolonged or repeated skin contact may produce severe irritation or dermatitis.
Aggravation of Pre-existing Conditions:
Use of alcoholic beverages enhances toxic effects. Exposure may increase the toxic potential of chlorinated hydrocarbons, such as chloroform, trichloroethane.
 
MEK is a "hotter" solvent. Note in the MSDS sheet that MEK will cause damage to the central nervous system with prolonged exposure. It's pretty nasty stuff.

Acetone is used for nail polish remover and is used by dermatologists as a skin degreaser. Obviously not as toxic as MEK, but I wouldn't be using it as a drink mixer either.

I use acetone or lacquer thinner if possible and only grab the MEK if the others won't cut it, so to speak.
 
Too Late

... MEK will cause damage to the central nervous system

MEK can't do more damage. We're already building and airplane in the garage aren't we?? :D

Seriously though, if given the choice, I'd use acetone. I believe it is higher on the solvents list that MEK, meaning acetone will disolve more compounds. Water, alcohol, acetone, ect I think is the starting order from high towards lower. Don't flame me if this is in error. I've used too much MEK in my life.
 
Last edited:
Chris... good point....

I went to the MSDS and they both look equally bad...:(



Compared to what? Acetone and MEk are both benign (relatively nontoxic) solvents, except for their high flammability rating. MEK is the better solvent as far as cutting epoxy/proseal goes. Both are excellent degreasers. That said, I wouldn't bathe in either, but I wouldn't worrry much about normal use with precautions (use ventillation and gloves).
 
Look on the ingrediant list

Look on the list of ingrediants on what ever it is you are trying to use the solvent on. If it is Acetone based than use acetone, if it MEK based then the best sovent is MEK, if water based then water will work best.
 
Bottom line is that both are hazardous in certain ways. Limit your exposure to both products anytime you can.
 
Chemist answer

Acetone and MEK are both ketones. Acetone is dimethyl ketone and MEK is methyl ethyl ketone. If you read the MSDS sheets on almost anything it gives hazards. They set out the worst case possible. Look up ethanol, the alcohol in beer, wine, etc. It is hazardous to breathe or consume it.

I have used large quantities of acetone in my work as a chemist. It is relatively benign. I'm 65 and healthy. Use good ventilation, wear suitable gloves (it removes oils from the skin and that will cause the skin to crack), and be aware it is volatile and very flammable. MEK is almost the same but it has a lower vapor pressure and therefore doesn't evaporate as quickly. I use MEK for that reason. They are equally good as solvents.

Look up lacquer thinner. It has hazardous material components. I think MEK is better.

Just be careful!

Larry Dickinson
 
Acetone and MEK are both ketones. Acetone is dimethyl ketone and MEK is methyl ethyl ketone. If you read the MSDS sheets on almost anything it gives hazards. They set out the worst case possible. Look up ethanol, the alcohol in beer, wine, etc. It is hazardous to breathe or consume it.

I have used large quantities of acetone in my work as a chemist. It is relatively benign. I'm 65 and healthy. Use good ventilation, wear suitable gloves (it removes oils from the skin and that will cause the skin to crack), and be aware it is volatile and very flammable. MEK is almost the same but it has a lower vapor pressure and therefore doesn't evaporate as quickly. I use MEK for that reason. They are equally good as solvents.

Look up lacquer thinner. It has hazardous material components. I think MEK is better.

Just be careful!

Larry Dickinson

Larry, thanks for your comments. I've stopped replying to posts that say MEK will kill on contact because it seems a lot of folks think that anything that smells as bad as MEK must be BAD! :)

MEK can be purchased at building supply stores from the same shelf as acetone, mineral spirits, and lacquer thinner. Common sense is prudent when dealing with any solvent.
 
Just curious: Is there anyone on this thread who DOESN'T use a respirator OR latex gloves when handling the hazarous substances?

All of the data sheets give details on how to use these substances properly. If people really are concerned about their effects, that suggests to me that people aren't properly protecting themselves in the first place. That, again it seems to me, is the first and safest step.
 
Just curious: Is there anyone on this thread who DOESN'T use a respirator OR latex gloves when handling the hazarous substances?

All of the data sheets give details on how to use these substances properly. If people really are concerned about their effects, that suggests to me that people aren't properly protecting themselves in the first place. That, again it seems to me, is the first and safest step.

Me!

I use a respirator and NITRILE gloves :rolleyes:
 
not Nitrile

Nitrile is a poor choice for both acetone and MEK. attached is a link for a recommended gloves chart. Butyl is preferred. There are others like silver shield gloves that offer very good resistance to permeation of the solvent through the glove, something a thin nitrile glove is poor at.

http://www.allsafetyproducts.biz/site/323655/page/74172

Also, respirator cartridges can become ineffective rather quickly, so change those often as well.
 
My 2 cents, from an old safety/environmental engineer- Unless you immerse your hands in liquid solvents for long periods (10+ minutes?), which we should not have to do very often, any "rubber" glove is probably ok as long as it is replaced when it expands and weakens, before breakthrough. These are not toxic chemicals we are working with, urethane paints and lacquer thinner excepted.

Silver shield gloves are impossible to work with anything tiny or that need some tactile feel- they are designed to support environmental remediation work inside of encapsulating suits, operating brooms and shovels.

Nitrile is probably a little better than butyl gloves with solvents, but, because we have to change gloves so often to keep contamination down, it probably does not matter much which type is used. Just do not allow excessive skin contact- to prevent irritation and dissolving oils out of your skin.

A respirator will not offer much protection unless you have installed new cartridge filters, of the correct type for the chemicals you are using. Most people don't have an assortment of chemical filters handy and assume that a dust shield offers protection against chemicals- they do not!
 
Read the fine print...

MEK

Skin Contact:
Causes irritation to skin. Symptoms include redness, itching, and pain. May be absorbed through the skin with possible systemic effects.
Eye Contact:
Vapors are irritating to the eyes. Splashes can produce painful irritation and eye damage.


ACETONE

Skin Contact:
Irritating due to defatting action on skin. Causes redness, pain, drying and cracking of the skin.
Eye Contact:
Vapors are irritating to the eyes. Splashes may cause severe irritation, with stinging, tearing, redness and pain.

I believe the arguments against MEK are associated with its higher risk of injury due to skin contact. The potential injuries from Acetone are listed as local irritation/dryness. MEK lists "possible systemic effects." That means the damaging chemicals can be absorbed thru the skin and disperse throughout your body.

I wear gloves and other protective clothing when I use dangerous chemicals, but accidents DO happen. Since it does the job just as well with less risk in the event of an accident, I'll stick with Acetone.

Regards,

Mark
 
Brambo; said:
What is the difference between Acetone and MEK. I have read in several discussions about fiberglass work where some people use acetone and others use MEK as a cleaner/thinner.
A credible source recommended that only acetone be used on canopy work. Don't know what MEK would do to the canopy.
 
MSDS' for acetone and MEK were likely written by different people, deciding on their own and using available research to guide them on what to say. Or maybe by the same person at different times. Two MSDS' written for the same substance by different people often look quite different. So I wouldn't put too much weight on the differences in skin effects. I would treat them with the same degree of caution and respect.
 
From an "Expert"

The following was posted on the Lancair Mail List.

QUOTE:

I have been involved in the fabrication and repair of advanced composite structures for over 20 years, having worked on such projects as the Lear Fan, the B-2 bomber, the Beech Starship, the C-17 cargo transport, and the Boeing 777. All of these aircraft rely heavily on advanced composite structures that are both bonded and fastened together.

Currently I am the Chief Technical Instructor at Abaris Training in Reno, NV. We offer training in bonding advanced composite and metal structures and I want to pass along the current standard practice for preparing a composite surface for bonding for your builders to ponder.

I must say that the methods of surface preparation for composite surfaces vary from one manufacturer to another but there are some common ideas amongst all of the major composite aircraft component manufacturers.

First, if the surface is not covered with a (non-release coated) peel-ply that can be removed to reveal a clean surface, then the surface should be cleaned free of contaminants prior to abrading. Acetone, isopropyl alcohol, MEK, or MIBK is usually specified for this task. (Methylene Chloride (MC) is not used by any of the big commercial manufacturers for numerous reasons.) I prefer acetone, as it is the least toxic of these solvents and is adequate for reducing most contaminants.

Wear the appropriate type of gloves when handling solvents! An organic vapor respirator is recommended for more extended exposure. (The 3M #8577 nuisance-level organic mask is affordable and protects the user well.) The surface to be prepared is ?double-wiped? with a clean solvent-soaked cloth in one hand and a clean, dry cloth immediately behind that. The dry wipe behind the solvent wipe helps pick-up the residual contaminants from the surface. Repeat as often as necessary with clean, fresh wipes to ensure good cleanliness. Allow the surface to dry thoroughly before abrading. This usually takes 15-20 minutes with good ventilation.

Next, abrade the surface with an appropriate abrasive that will raise the surface-free energy of the matrix resin but will not damage the fibers at the surface. Usually 3M?s ScotchBrite? # 7447 pads are used for this purpose. Optionally, #320 or #400 grit sandpaper may be used on non-textured surfaces. A thorough abrasion is best accomplished by abrading in a multi-directional manner. It takes a bit of work to do a good job by hand. The surface should be uniform in appearance all along the length of the joint.

Clean the dust off of the surface with a clean, dry piece of Rymplecloth?, or an equivalent (non-chemical treated) cheesecloth material. Repeat the dry-wipe procedure with fresh cloths several times until no dust residue remains. (This non-solvent approach is becoming more mainstream in the aerospace industry as the risk of introducing additional contaminants or moisture, or changing the surface energy with the solvent is of major concern.)

If you must use a solvent, then reagent grade acetone is probably the best choice. Purchase small pint-size cans and keep the lid tightly secured when not using the stuff. This will reduce the potential for moisture uptake in the stored solvent. Be aware that any solvent used at this point may bring moisture onto the surface; so follow the double-wipe method as described earlier. If there is a ?milky? look to the surface after wiping, it is probably moisture. This is usually noticeable when the relative humidity is greater than 50%.

After cleaning, it is suggested that the adhesive be applied and the joint closed and clamped as soon as possible. The longer you wait, the more the surface has a chance to stabilize, thus reducing your surface-free energy and diminishing your covalent exchange between the surface and the adhesive.

If anybody is interested in learning more about this, or other composite related subjects, I invite you to come take a class at our Reno, NV, or our Griffin, GA facilities. It may be well worth your time. You can visit our web site for more information: www.abaris.com.

Louis C. Dorworth
Chief Technical Instructor
Abaris Training Resources, Inc.
5401 Longley Ln. #49
Reno, NV. 89511
Phone: (775) 827-6568
Fax: (775) 827-6599
e-mail: [email protected]

END QUOTE
 
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